Ios Interview Questions

 

Automatic reference counting | What is swift ARC | Memory management in swift

Code:-

class Person
	{
	var name: String
	weak var job: Job? // Weak to remove the reference count or Retin count
	init(_name: String) {
	debugPrint("init method of Person called")
	name = _name
	}
	func printName() {
	debugPrint("name is \(name)")
	}
	deinit {
	debugPrint("deinit called for person class")
	}
	}
	class Job
	{
	var jobDescription: String
	weak var person: Person?
	init(_jobDescription: String) {
	debugPrint("init method of Job called")
	jobDescription = _jobDescription
	}
	deinit {
	debugPrint("deinit called for job class")
	}
	}
	if (1 == 1)
	{
	let objPerson = Person(_name: "codect15")
	let objJob = Job(_jobDescription: "swift programmer")
	objPerson.job = objJob
	objJob.person = objPerson
	} protocol and  Genric Class also Conditional conformance in swift example import UIKit protocol Bird {     func fly()      } // optional protocol extension Bird {     func fly() {         print("fly like a bird")     } } class Parot: Bird { } class Crow: Bird { } protocol Machine  {          func start()   } class Aerplane: Machine , Bird {           func start() {              }     func fly() {         print("fly like an Aeroplane")     }           } let objCrw = Crow() let objParot = Parot() let objAero = Aerplane() var arrOjec : [Bird] = [objCrw, objParot, objAero] var arrItem = [1, 2, 4] /// Genric Class class Bag<T> {     var item:[T] = []          func addElement(element:T) {         item.append(element)     }     func removeLast()-> T {                  return  item.removeLast()     }             } /// Genric Class Conditional conformance  extension Bag where T == Int {     func getSum()->Int {         let sum = item.reduce(0, +)        return sum     } } var objBag = Bag<Int>() var objBag2 = Bag<String>() objBag.addElement(element: 23) objBag.getSum() for item in arrOjec {     item.fly() } print("Working")

 Find the Index of element in Array in swift.

        swift 5 , Swift 4.2 

        As a swift find the element in array without pre-define function.

   

     As a swift find the element in array with pre-define function.

 

Program for array rotation In Swift.

 

METHOD 1 (Using temp array) 

METHOD 2 (Rotate one by one)

METHOD 3 (A Juggling Algorithm) 

Find the Missing Number

Method 1: This method uses the technique of the summation formula. 

• Approach: The length of the array is n-1. So the sum of all n elements, i.e sum of numbers from 1 to n can be calculated using the formula n*(n+1)/2. Now find the sum of all the elements in the array and subtract it from the sum of first n natural numbers, it will be the value of the missing element.
• Algorithm: 
1. Calculate the sum of first n natural numbers as sumtotal= n*(n+1)/2
2. Create a variable sum to store the sum of array elements.
3. Print the missing number as sumtotal – sum